A trimmer is described in Patent Document 1 (JP2016-221619A) as a three-side trimmer. The three-side trimmer is used so as to trim each of top edge, bottom edge and fore-edge areas of a bound material during a finish processing of a book binding process. The bound material includes a book block and a cover attached on the book block.
As shown in FIG. 1 of Patent Document 1, in case of the three-side trimmer, the bound material 1 is conveyed by a belt conveyer 100 so as to be positioned by abutting against a first positioning part 110. The trimmer includes a pusher 2 disposed on the fore-edge area 1a side of the bound material 1. The bound material 1 positioned by the first positioning part 110 is pushed by the pusher 2 so as to be conveyed toward a fore-edge trimming part 52 that trims the fore-edge area of the bound material 1.
The fore-edge trimming part 52 includes a fore-edge trimming blade 3. The bound material 1 conveyed to the fore-edge trimming part 52 is positioned in such a way that the fore-edge area 1a of the bound material 1 is disposed below the fore-edge trimming blade 3. The fore-edge trimming blade 3 falls toward a trimming position from a non-trimming position so as to trim the fore-edge area 1a of the bound material 1. The bound material 1 comprising the trimmed fore-edge area 1a is gripped by a chuck device 15 so as to be conveyed toward a top and bottom edges trimming part 53 that trims the top and bottom edges 1b and 1c of the bound material 1.
By the way, each of the bound materials 1 may be different respectively in length since errors occur with respect to the amount of the folding of the papers of the bound material 1, the amount of the glue applied on the paper of the bound material 1, the amount of the milling of the bound material 1 and so on when making the bound material 1 before trimming it. There is no problem when the length of the bound material 1 before trimmed is in the allowable range (normal case). On the other hand, there is a problem when the length of the bound material 1 before trimmed is large or small beyond the allowable range (abnormal case).
In the three-side trimmer, a position where the pusher 2 should be stopped is preset depending on the length of the bound material 1 before trimmed. However, there is a problem that the bound material 1 cannot be trimmed precisely since the bound material 1 cannot be positioned correctly when the length of the bound material 1 before trimmed is abnormal.
Patent Document 1: JP 2016-221619 A